The present invention relates to an optical information recording medium for recording and retrieving said information, and particularly to an inorganic optical information recording composition as a recording layer of said optical information recording medium.
The recording layer materials for recordable optical recording disks currently available on the market mainly are cyanine dyes, phthalocyanine dyes, and azo dyes. The synthesis and purification of these organic dyes require complicated steps and the production costs thereof are thus relatively high.
The pursuit of a higher recording density is a trend of development for a recordable optical recording disk. Along with the development of the recording density, the recording mark will become smaller, and the selection of the material for the recording layer will be more stringent. In particular, there are very few organic dyes available for use as a recording layer material in short wavelength laser (e.g. 405 nm blue laser) and high speed recording ( greater than 2X DVD) applications. To the knowledge of the inventors of the present invention, there is only one novel organic dye responsive to the blue light, which is published by Sony Co. of Japan in the ISOM Conference in 2001 [T. Iwamura et al., Technical Digest of Intrnational Symposium on Optical Memory 2001, p218-219]. Sony Co. proposes a vacuum evaporation process for forming a HD-DVD-R organic dye recording layer instead of the spin coating process conventionally used in mass production by the optical recording disk factories. The reason is that the track pitch of a high density HD-DVD-R is about one half of that of a low density DVD-R optical recording disk. If the spin coating process is used, the deep grooves on the substrate cannot be completely filled with the dye. However, the evaporation process still requires more studies to be put into mass production with comparable cost.
The use of an inorganic material as a recording layer material for a recordable optical recording disk has been disclosed in U.S. Pat. No. 5,334,433, 6,229,785B1 and US2002/0022105A1. The Te-O-Pd recording layer material disclosed by Matsushita Co in U.S. Pat. No. 6,229,785B1 and US2002/0022105A1 possesses a relatively greater commercial potential. When the inorganic material is used to form the recording layer, one advantage among others is the vacuum sputtering process currently used by the optical recording disk factories is applicable. The vacuum sputtering process uses less man-power, is more friendly to the environment, and is easier to control the film quality. To realize the production of a high-density, high-speed, and multi-recording-layer optical recording disk, an inorganic material is more feasible than an organic material as a recording layer material.
One objective of the present invention is to provide a novel inorganic optical information recording composition, so that an optical information recording medium manufacturer has another option to choose a recording layer material.
Another objective of the present invention is to provide an optical information recording medium with a high speed and a high recording density, while having an excellent recording and reading properties such as a high carrier-to-noise ratio (CNR) and a low jitter.
The present invention uses inorganic Sbxe2x80x94N or Sbxe2x80x94Nxe2x80x94M (N-containing series), Sbxe2x80x94O or Sbxe2x80x94Oxe2x80x94M (O-containing series), or Sbxe2x80x94Nxe2x80x94O or Sbxe2x80x94Nxe2x80x94Oxe2x80x94M (N/O-containing series) as a recording layer material for a recordable optical recording disk, wherein M is one or more elements selected from Ge, Te, Bi, Sn, Ag, Au, In, Pb, Pd, Pt, Al, Si, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ta, Ga, Zr, Nb, Mo, Ru, Rh, Hf, W, Re, Os, Ir, Dy, Tb. A high density recordable optical recording disk can be produced by sputtering such a material on a transparent substrate having annular-grooved tracks, and sputtering a metallic reflective layer and a protective layer thereon. A reactive sputtering can be used to form the recording layer material of the present invention, wherein a target used is made of Sb element or an Sb alloy thereof, Sbxe2x80x94M. During sputtering of the recording layer, argon and nitrogen (or argon and oxygen; or argon, nitrogen and oxygen) are introduced into the reaction chamber at the same time, wherein a DC- or RF-sputtering is used. The composition and thickness of the recording layer can be controlled so that said recording layer has a sufficient absorption in the ultraviolet region, the blue-violet region, or the visible region, such that a light beam with a wavelength of 200-800 nm can be used to record and retrieve information.